MASTER AND PUPIL
the world. One phase of these interests demands more than the
passing reference that might suffice in a purely scientific bio-
graphy of Weierstrass: his friendship with his favourite pupil,
Sonja (or Sophie) Kowalewski.
Madame' Kowalewski's maiden name was Sonja Corvin-
Kroukowsky; she was born at Moscow, Russia, on 15 January
1850, and died at Stockholm, Sweden, on 10 February 1891, six
years before the death of Weierstrass.
At fifteen Sonja began the study of mathematics. By eigh-
teen she had made such rapid progress that she was ready for
advanced work and was enamoured of the subject. As she came
of an aristocratic and prosperous family, she was enabled to
gratify her ambition for foreign study and matriculated at the
University of Heidelberg.
This highly gifted girl became not only the leading woman
mathematician of modern times, but also made a reputation as
a leader in the movement for the emancipation of women,
particularly as regarded their age-old disabilities in the field of
In addition to all this she was a brilliant writer. As a young
girl she hesitated long between mathematics and literature as a
career. After the composition of her most important mathe-
matical work (the prize memoir noted later), she turned to-
literature as a relaxation and wrote the reminiscences of her
childhood in Russia in the form of a novel (published first in
Swedish and Danish). Of this work it is reported that 'the
literary critics of Russia and Scandinavia were unanimous in
declaring that Sonja Kowalewski had equalled the best writers
of Russian literature in style and thought.' Unfortunately this,
promising start was blocked by her premature death, and only
fragments of other literary works survive. Her one novel was
translated into many languages.
Although Weierstrass never married he was no panicky
bachelor who took to his heels every time he saw a pretty
woman coming. Sonja, according to competent judges who
knew her, was extremely good-looking. We must first tell how
she and Weierstrass met.
WeJerstrass used to enjoy his summer vacations in a thor-